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Weak DOCSIS 3.1 signal but OK DOCSIS 3.0 signal

Daveoc644
Joining in

For about a week now I've noticed packet loss on my connection.

Back on Tuesday/Wednesday the automated phone line reported that there was a fault in the area.

I got a text message yesterday morning saying that the fault has been corrected, but nothing has improved. The line no longer reports any faults (like the website).

My 3.1 downstream channel seems to have a really weak signal since this started.

BQM shows little packet loss in the last 24 hours:

https://www.thinkbroadband.com/broadband/monitoring/quality/share/63bbe1da56d09add6cedbb5467e045c98a...

I've tried all the obvious things like making sure everything's plugged in and rebooting the Hub 4.

I'm pretty sure this will need an engineer.

3.0 Downstream channels

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID

253310000005.19999736.609653QAM25625
102110000001.59999836.386890QAM25610
112190000002.00000036.386890QAM25611
122270000002.50000036.609653QAM25612
132350000003.50000036.386890QAM25613
142430000004.09999836.609653QAM25614
152510000004.00000036.609653QAM25615
162590000004.30000336.609653QAM25616
172670000004.59999836.609653QAM25617
182750000005.09999836.609653QAM25618
192830000005.19999736.386890QAM25619
202910000005.19999736.609653QAM25620
212990000005.30000336.609653QAM25621
223070000005.30000336.609653QAM25622
233150000005.30000336.609653QAM25623
243230000005.19999736.386890QAM25624
263390000005.00000036.386890QAM25626
273470000004.59999835.779911QAM25627
283550000004.69999735.779911QAM25628
293630000005.09999835.779911QAM25629
303710000005.59999835.779911QAM25630
313790000006.09999835.779911QAM25631
323870000006.50000035.779911QAM25632
333950000006.30000335.595078QAM25633
344030000006.00000035.595078QAM25634
354110000005.90000235.779911QAM25635
364190000006.09999835.595078QAM25636
374270000006.50000035.595078QAM25637
384350000006.80000335.779911QAM25638
394430000007.00000035.595078QAM25639
404510000006.90000235.779911QAM25640



3.0 Downstream channels

Channel Lock Status RxMER (dB) Pre RS Errors Post RS Errors

25Locked36.60965300
10Locked36.38689000
11Locked36.38689000
12Locked36.60965300
13Locked36.38689000
14Locked36.60965300
15Locked36.60965300
16Locked36.60965300
17Locked36.60965300
18Locked36.60965300
19Locked36.38689000
20Locked36.60965300
21Locked36.60965300
22Locked36.60965300
23Locked36.60965300
24Locked36.38689000
26Locked36.38689000
27Locked35.77991100
28Locked35.77991100
29Locked35.77991100
30Locked35.77991100
31Locked35.77991100
32Locked35.77991100
33Locked35.59507800
34Locked35.59507800
35Locked35.77991100
36Locked35.59507800
37Locked35.59507800
38Locked35.77991100
39Locked35.59507800
40Locked35.77991100



3.1 Downstream channels

Channel Channel Width (MHz) FFT Type Number of Active Subcarriers Modulation (Active Profile) First Active Subcarrier (Hz)
41964K1840QAM1024759


3.1 Downstream channels

Channel ID Lock Status RxMER Data (dB) PLC Power (dBmV) Correcteds (Active Profile) Uncorrectables (Active Profile)
41Locked33-13.0728771500

 

3.0 Upstream channels

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID
12360000044.2705995120 KSym/sec32QAM10
24960000047.0205995120 KSym/sec64QAM6
34310000046.0205995120 KSym/sec64QAM7
43660000045.5205995120 KSym/sec64QAM8
53010000045.5205995120 KSym/sec64QAM9



3.0 Upstream channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts
1US_TYPE_ATDMA0000
2US_TYPE_ATDMA0000
3US_TYPE_ATDMA0000
4US_TYPE_ATDMA0000
5US_TYPE_ATDMA0000



3.1 Upstream channels

Channel Channel Width (MHz) Power (dBmV) FFT Type Modulation
1210.843.02KQAM128


3.1 Upstream channels

Channel Channel Type Number of Active Subcarriers First Active Subcarrier (Hz) T3 Timeouts T4 Timeouts
12OFDMA22053.400
1 ACCEPTED SOLUTION

Accepted Solutions

Gareth_L
Forum Team
Forum Team

Hello Daveoc644.

Thanks fort those details.

I have booked the Technician to attend and sent the date by private message.

Can you please let us know how the visit goes.

Gareth_L

See where this Helpful Answer was posted

6 REPLIES 6

Tudor
Very Insightful Person
Very Insightful Person

That is low and there is one upstream on 32QAM that is wrong.

Check with Area faults on 0800 561 0061 If you have a VM landline 150 this goes down to post code level. You could also try the web page status, but this is not recommended as it only covers issues that affect a very large number of customers.

VM will not dispatch any technicians while an area fault exists.

If no area faults found:

The primary place to report faults or for service requests is Customer Services on 0345 454 1111/150 if you have a VM landline or wait two or three days for a VM staff member to get to your post.


Tudor
There are 10 types of people: those who understand binary and those who don't and F people out of 10 who do not understand hexadecimal c1a2a285948293859940d9a49385a2

Gareth_L
Forum Team
Forum Team

Hello Daveoc644,

Thank you very much for popping back on our Community.
Can I just apologise for service issues with your broadband.
We can run a few tests from here and check on your equipment.
Sadly it is showing an issue with the downstream power levels, So I will need to send you a private message to gain account access and arrange an engineers visit.
If you can check the purple envelope top right of your screen that would be great. 
Regards     
Gareth_L
 

Going by the roll off looks like there's a component in the line somewhere that tops out at 750 MHz.

If there isn't a very old attenuator in the home and others are seeing the same thing one for access networks.

HFC/CATV components top out at 550, 750, 860, 1000, 1218 and 1800 MHz. When VM did an upgrade in the area to make the room for the 3.1 downstream they may have missed an amplifier so left the customers served by it restricted to 750 MHz. The 3.1 signal is above that so isn't getting amplified with the rest.

Looks a lot like when the area's network was upgraded a 750 MHz component was left in place leaving the spectrum above partially amplified. Given the 3.1 signal starts at 759 MHz there's going to be a big roll off there.

One for networks. 

Gareth_L
Forum Team
Forum Team

Hello Daveoc644.

Thanks fort those details.

I have booked the Technician to attend and sent the date by private message.

Can you please let us know how the visit goes.

Gareth_L


@IPFreely wrote:

Looks a lot like when the area's network was upgraded a 750 MHz component was left in place leaving the spectrum above partially amplified. Given the 3.1 signal starts at 759 MHz there's going to be a big roll off there.

One for networks. 


That's an interesting theory, but we've had DOCSIS 3.1 channels on both downstream and upstream for a long time, and the power levels across everything were always OK until about two weeks ago.

 

Will have to wait and see what the engineer thinks!